Sock it.

You can't fool your feet.  When my feet get cold at night, and I'm already in bed, I try to warm my feet by wrapping them in the sheet, then the blanket, and finally all the bedding at once, even the comforter.   It never works; I still need to get up and put on a pair of socks, which never fails to bring instant comfort.  You'd think I'd have learned, after all this time, but I still live in hope that if I can pile multiple layers of cloth around my feet, and  wrap them snugly enough, that my feet will get warm.  I don't really understand why not.